In the past, there has been an uninterruptible power supply unit that is connected to an apparatus including two types of power supply input and supplies two types of power supply to the apparatus. The uninterruptible power supply unit includes a first power supply input unit and a second power supply input unit, to which two respective types of power supply are input, and a first power supply output unit and a second power supply output unit, which output the respective power supplies input to the first power supply input unit and the second power supply input unit. The uninterruptible power supply unit further includes a control unit that detects power failure states of the power supplies input to the first power supply input unit and the second power supply input unit and causes, based on the detection result thereof, a backup power supply to be output from at least one power supply output unit of the first power supply output unit and the second power supply output unit.
By the way, in case that both the two types of power supply are put into power failures, the uninterruptible power supply unit of the related art includes a battery charged with direct-current power, and an inverter converting the direct-current power output from the battery into alternating-current power.
The following is a reference document.    [Document 1] Japanese Laid-open Patent Publication No. 2004-254470.